Have you considered that density itself is a contributing factor? That's hardly a stretch. Perhaps certain effects will be magnified in cities compared to rural areas or states containing both. And those cities might also tend more toward the Democrat end of the political spectrum. Correlation still does not equal causation. The whole "failed cities are X" trope doesn't suggest any useful policy either, unless you think emulating China's "Down to the Countryside" movement would be a great idea.

I contend that, adjusting for density, places like Mississippi or Appalachia stand as stark counterexamples to any theory that being "blue" leads to failure. In fact, a pretty strong argument could be made that "blue" policies around things like public vs. private goods, fossil vs. renewable energy, or respect for immigrants are the only reason urban failures haven't been worse or more widespread. Believe it or not, Detroit could be worse, and I believe would be worse if certain "heartland" attitudes were more prevalent there. Literal "smoking hole in the ground" worse.

To bring this back to the original topic, the inevitable trend toward greater urbanization therefore means it's even more important to address gerrymandering now instead of kicking the can down the road. Letting the rural few dictate to the urban many will surely lead to heartbreak and pain, no matter what other beliefs are involved.